Digital subscriber line (xDSL) equipment operated by service providers typically provides communication services for many customers. To provide simultaneous service to these customers, this equipment often has racks containing multiple xDSL communications cards. Physical requirements of the cards and industry standards can limit the number of devices that may be packed into an equipment rack. The power consumption of xDSL communications cards represents one of the primary limitations on the number of devices that may be located in a given area. Reduced power consumption reduces interference among closely spaced cards, reduces cooling requirements, and thus allows for increased density of devices in an equipment rack.
Moreover, the network equipment building standard (NEBS) specification developed by Bell Communications Research (BELLCORE) provides minimum industry standards for different telephony components, including xDSL communications equipment. These standards detail specific requirements for a NEBS compliant rack, such as the amount of power that it may consume and specific cooling requirements. Therefore, the power consumption of xDSL communications cards directly affects the number of these devices that may be contained in a NEBS compliant system.